Process for stabilizing structure of ground meat

ABSTRACT

Stabilization of the structure of shaped, cooked, ground meat which is to be sterilized with high energy ionizing radiation is accomplished by incorporating within raw, ground meat from 0.5 percent to 1.5 percent by weight of sodium chloride and from 0.25 to 1.0 percent by weight of a food grade phosphate.

United States Patent Shults et al.

[ Feb. 15, 1972 [54] PROCESS FOR STABILIZING STRUCTURE OF GROUND MEAT[72] inventors: Gary W. Shults, Milford; Eugen Wierbicki,

Framingham, both of Mass.

[73] Assignee: The United States of America as representedbytheSecretary oi the Army 22 Filed: July 17,1969

21 Appl.No.: 842,703

[52] 11.8. CI.... ..99/108, 99/157 [51] Int. Cl. ..A22C 18/00, A23b H00[58] Field ofSearch ..99/108, 109, 159, 174, 217,

[56] References Cited UNITED STATES PATENTS 2,456,909 12/1948 Brasch.....99/ 221 x 2,513,094 6/1950 Hall ..99/159 3,483,005 12/1969 Urbainet a1. ..99/217 3,076,713 2/1963 Maas ..99/159 X 3,554,773 1/1971 Shultset al. ..99/217 Stabilization of the structure of shaped, cooked, groundmeat which is to be sterilized with high energy ionizing radiation isaccomplished by incorporating within raw, ground meat from 0.5 percentto 1.5 percent by weight of sodium chloride and from 0.25 to 1.0 percentby weight of a food grade phosphate.

5 Claims, No Drawings PROCESS FOR STABlLlZlNG STRUCTURE OF GROUND MEATThe invention described herein may be manufactured, used and licensed byor for the Government for governmental purposes without the payment tous of any royalty thereon.

This invention relates to a process for stabilizing the structure ofshaped ground meat which is cooked and then sterilized with high energyionizing radiation.

1n connection with the sterilization of ground meat items with highenergy ionizing radiation, it has been observed that the irradiatedground meat product loses its natural cohesive properties and crumblesinto small fragments. While shaped ground meat products, especiallypatties, are widely accepted food items, it is obvious that if suchproducts fall apart rather than remain intact, consumer appeal willdiminish. Sterilization of ground meat with high energy ionizingradiation is preferable to thermal sterilization since the resultingproduct does not have that characteristically overcooked quality ofthermally processed meat. in view of the failure of the ground meat itemto hold together when subjected to a sterilizing does of ionizingradiation, attempts have been made to incorporate binders which wouldcompensate for the loss of the natural binding properties of the meat.The common binders used in connection with meat products are starch orprotein binders obtained from cereal products, such as soy protein, cornstarch, potato starch, etc. The addition of cereal binders to groundmeat is a decided disadvantage when the meat is processed with highenergy ionizing radiation, since such binders cause discoloration,off-odors and irradiation flavors.

We have discovered that by incorporating sodium chloride and a foodgrade phosphate into the ground meat, the shape structure will bemaintained following exposure to a sterilizing dose of high energyionizing radiation and that the organoleptic properties of the groundmeat will not suffer as in the case of the cereal binders. Sodiumchloride is added to the ground meat in an amount which ranges from 0.5percent to 1.5 percent by weight based on the weight of the meat. Amongthe food grade phosphates which may be used are sodium tripolyphosphate,sodium hexametaphosphate, tetrasodium pyrophosphate and mixtures of theforegoing phosphates such as a mixture of sodium hexametaphosphate (67percent) and sodium tripolyphosphate (33 percent). The food gradephosphate is added in an amount which varies within the range of 0.25percent to 1.0 percentby weight based on the weight of the meat. Thesalt and the phosphate may be added separately or may be mixed togetherand then incorporated in the ground meat. 1t is essential, however, thatboth the salt and the phosphate be added to the ground meat while in itsraw state and that the additives be asuniformly distributed within meatas is possible.

Any grade of beef or any other kind of meat, e.g., pork, lamb, veal,poultry, may be employed in the practice of this invention. Grinding ofthe meat is accomplished by conventional means known in the art, and thedegree of fineness of the grind will depend in part on the preference ofthe user and the type of food item. We normally use /2 inch and 3/16inch grinding plates. After grinding, the salt and phosphate are addedand thoroughly blended with the ground meat which is then shaped intothe desired form such as patties, ground meat rolls, meat balls, etc.The shaped, ground meat product is then cooked to develop thecharacteristic flavor of cooked meat and also to inactivate theproteolytic enzymes present. To inactivate such enzymes, it is necessaryto bring the internal temperature of the product within the temperaturerange of 65 to 85 C. and preferably to 70 C. Cooking is accomplished byoven baking, grilling or deep fat frying. Following the cooking step,the product is packaged under vacuum in a suitable rigid or flexiblecontainer.

Sterilization of the vacuum packed product is performed at temperaturesbelow C. and preferable within the range of 30 to -80 C. Sterilizationis accomplished by exposing the foodstuff to a sterilizingdose of highenergy ionizing radiation having energy levels that range from 750,000electron volts to about 10,000,000 electron volts. The types of ionizingradiation that may be used are known in the art and may include, forexample, electron beams, gamma rays, x-rays. It is preferred that theenergy level of the ionizing radiation be less than 12,000,000 electronvolts in order to avoid any possibility of inducing radioactivity in thefood items treated. Sterilization of food stuffs requires dosages ofionizing radiation in the range of approximately 2.0 to about 6.0megarads. Rad is a unit of absorbed dose of ionizing radiation equal toan energy of 100 ergs per gram of irradiated material.

Irradiation of the food items in the following examples was accomplishedby exposing the items to gamma radiation from a 900,000 curie Cobalt 60source. The physical arrangement of the source consisted of twospaced-apart parallel plaques which contain the radioisotope. Samplesare carried by a conveyor between the plaques for an interval of timenecessary to reach the desired dosage level.

Our invention will be described in more detail in connection with thefollowing example setting forth the process for preparing an irradiated,shelf-stable, cooked, ground beef pattie.

EXAMPLE 1 Beef round muscle, U.S. choice grade, 7 days after slaughter,was cut into chunks which were then fed into a commercial meat grinderhaving a 3/16 inch grinding plate. The ground beef was reground throughthe same machine. After grinding, 1 percent by weight of food gradesodium chloride and 0.5 percent by weight of food grade sodiumtripolyphosphate were added to and completely mixed into the raw groundbeef. The ground beef was then formed into circular patties,approximately 4 oz. in weight which were placed on cooking pans andinserted in an oven, heated to 350-400 F., and cooked for 4 minutes onone side and 2 minutes on the other side which was sufficient to bringthe internal temperature of the pattie to 70 C. Six cooked patties arestacked within a cylindrical metal container and sealed under 25 inchesof vacuum. The sealed containers are transferred to the radiation sourceand the temperature of the contents of the containers brought down to C.in a cold box. The containers, while held at -80 C. are then subjectedto 4.5-5.6 megarads of high energy ionizing radiation in the form ofgamma rays from 900,000 curie Cobalt 60 source.

A duplicate set of samples were prepared as in the previous paragraph,except that the sodium chloride and sodium tripolyphosphate were notadded to the meat. Eight containers containers containing six pattieseach, were compared with a similar number of patties prepared accordingto this invention. A visual examination of the samples indicated thatthe patties prepared with the combination of NaCl and Na Tpp were firmand intact with no crumbling whereas the samples prepared without theadditives of this invention, had crumbled to such an extent that theywere virtually unrecognizable as patties.

We claim:

1. A process for stabilizing the structure of shaped ground meat whichis cooked and then sterilized with high energy ionizing radiation whichcomprises in sequence the steps of a. uniformly incorporating within rawground meat from 0.5 percent to 1.5 percent by weight of sodium chlorideand from 0.25 percent to 1.0 percent by weight of a food gradephosphate,

b. forming the raw ground meat into the desired shape,

c. cooking the shaped ground meat to an internal temperature of from 65C. to C. to inactivate the proteolytic enzymes and develop thecharacteristic flavor of cooked meat,

d. packaging said cooked, shaped ground meat under vacuum, and

e. sterilizing the cooked, shaped ground meat by means of high energyionizing radiation within the dosage range of from 2.0 to 6.0 megarads,while said meat is maintained at a temperature below 0 C.

2. Process according to claim 1 wherein the food grade phosphate isselected from the group consisting of sodium tripolyphosphate, sodiumhexametaphosphate, tetrasodium pyrophosphate and mixtures thereof.

4. Process according to claim 3 wherein 0.5 percent by weight of thefood grade phosphate and 1.5 percent by weight of sodium chloride isadded to the ground beef.

5. Process according to claim 4 wherein the food grade 3. Processaccording to claim 2 wherein the ground meat is 5 Phosphate istelrasodium PY P P beef.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.5,642,500 Dated February 15,1972

Gary W. Shults et a1 Inventor(s) It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

The term of this patent subesquent January 21, 1988, has beendisclaimed.

(SEAL) Attest:

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officerand Trademarks FORM PO-1OS0 10-69) uscoMM-oc e0a7e-pe9 u.s GOVEHNMENIPRINTING OFFICE: 930

2. Process according to claim 1 wherein the food grade phosphate isselected from the group consisting of sodium tripolyphosphate, sodiumhexametaphosphate, tetrasodium pyrophosphate and mixtures thereof. 3.Process according to claim 2 wherein the ground meat is beef.
 4. Processaccording to claim 3 wherein 0.5 percent by weight of the food gradephosphate and 1.5 percent by weight of sodium chloride is added to theground beef.
 5. Process according to claim 4 wherein the food gradephosphate is tetrasodium pyrophosphate.